Engine/Transmission (1998.5 - 2002) Sick Turbo? -> Bad Gas Mileage?

[azcummins]

I've noticed a new sound eminating from my transmission area that sounds like my turbo is sick. The turbo still has the high pitched whistle as always, but now there is a lower tone that sounds like the turbo is just "sick" or even "gurgling". Even though the sound is coming from my transmission area, I know it isn't the transmission, b/c I only get the sound when the turbo is producing more than about 7 psi of boost. Oddly enough, the sound disappears when I get around 20 psi. Also, I don't get the sound all the time.



My turbo is still producing 28 psi of boost so my turbo doesn't seem like it might be sick or going out, but I've noticed my gas mileage has hit the pits. I drove 5 miles tonight on the interstate and my needle went from full to 7/8 of a tank.



I'm scratching my head on this one. Any ideas?

 

[IMunro]

Sick turbo

Check the boots from the turbo to the intercooler, both into it and out of it. I had poor mileage, about 17-18 plus high ex. temps, and when I was changing my oil I noticed that the boot connector from the turbo to the intercooler was not completely captured by the band and had a significant pucker. I have no idea what percentage of the air-charge was escaping, but after I fixed it the performance made a good jump and my mileage went up to 21. 5, which is more what i would have expected since I am stack with a 3. 55 and 2WD.



I don't have a lot of experience with these trucks, having only had it since Feb of this year, but the above is what happened to me.



Now if I could only figure out why my transmission temp is so high, I'd be happy. Probe is on line to cooler and unloaded up a fairly long hill the guage climbs to 230 deg. I was in 1st or 2nd most of the time as it was a bit of a switchback with a costruction zone a lot of the way. Mt Baker Highway in Western Wash to and past the Summit, maybe 6000' tops. Also in traffic, empty, it often gets over 200, if I am sitting at idle. I move shifter to neutral but it doesn't seem to help.



Any ideas? Is a disaster in my future? Is this normal? Thanks for any input.



ianonhercules

 

[Hohn]

You might also want to check for boost leaks at the gauge plumbing or intake hat gaskets...

 

[rblomquist]

Now if I could only figure out why my transmission temp is so high, I'd be happy. Probe is on line to cooler and unloaded up a fairly long hill the guage climbs to 230 deg. I was in 1st or 2nd most of the time as it was a bit of a switchback with a costruction zone a lot of the way. Mt Baker Highway in Western Wash to and past the Summit, maybe 6000' tops. Also in traffic, empty, it often gets over 200, if I am sitting at idle. I move shifter to neutral but it doesn't seem to help.



ianonhercules

I'm assuming you're running a auto trans? If you are and you are in 1st or 2nd gear the TC will not be in lockup i. e. you're in fluid coupling which causes the temps to rocket especially when you add in poor airflow through the cooler because of the low speed. Same thing while tromped into passing gear, and when you're off the throttle, coasting etc (computer tells the TC to remain unlocked). Also, there's some slippage of the stock TC even when locked up if you're pulling a heavy enough load and/or have more juice getting put to the ground.



I've been down that road and have the scars for it. The only good thing that came out of it is that I now have a very nice transmission now but it was painfull to foot the bill.

 

[ESwartzer]

AZ I had very similar symptoms as you do. Terrible mileage, and sick turbo sound! During inspection , I found a loose intercooler hose clamp , tightened it and my mileage increased to 16. 5 on the road. I still had the sick turbo sound, and a stinking exhaust with lots of unburned fuel in it. So!! On a calculated whim , I replaced my IAT sensor ,reset my APPS and whaddya know ! My turbo sounds clean again, and my road mileage is just over 20mpg ,Best its ever been!! Eswartzer

 

[azcummins]

I checked my intercooler hoses and they are all tight. I'm thinking it is an exhaust leak and my mileage has recovered, my boost #'s are still right, but I've still got the sounds. Even more odd is that I don't get the sound everytime the turbo spools up.

 

[BlakeDavis]

as crazy as this may sound, you might check the u-joints, had a simialar situation, minus the mileage loss, i would get a strang noise that i thought was related to the turbo because it would come and go with throttle position. for some reason i decided to check my u joints and when i did one of them was quite a bit warmer than normal, replace and the sound was gone,